function xdot = mySys(x,t)
# Sample EOM for a mass on a spring
# in a (constant) gravity field, with damping

m = 5; # mass, kg
g = 9.81; # gravity, m/s^2
k = 10; # spring constant, N/m
c = 0.3; # damping coefficient, N.s/m

xdot(1) = x(2); # velocity
xdot(2) = -m*g - c*x(2) - k*x(1); # acceleration

return
